This invention relates generally to gas turbine engines and more particularly, to cooling combustor assemblies for use with gas turbine engines.
At least some known gas turbine engines use cooling air to cool a combustion assembly within the engine. Often the cooling air is supplied from a compressor coupled in flow communication with the combustion assembly. In at least some known gas turbine engines, the cooling air is discharged from the compressor into a plenum extending at least partially around an impingement sleeve and a flow sleeve which extends over a transition piece and combustor liner, respectively, of the combustor assembly. Cooling air from the plenum flows through inlets of these sleeves and enters into cooling passages that are defined between the impingement sleeve and the transition piece (the transition passage) and between the combustor liner and flow sleeve (the liner passage). Cooling air flowing through the transition passage is discharged into the liner passage. Cooling air from the plenum is channeled through inlets of the sleeves into the liner passage in order to cool the combustor assembly. The cooling air, which is heated by the metal surface of the transition piece and/or the combustor liner, is then mixed with fuel for use by the combustor.
It is desirable that the combustion liner and transition piece are evenly cooled in order to protect the mechanical properties and prolong the operative life of the combustion liner and transition piece. At least some known flow sleeves and impingement sleeves include inlets that are shaped or configured to facilitate the flow of cooling air through them. Other inlets are filled with open-ended thimbles that are configured to direct the cooling air into the cooling passages at an angle that is substantially perpendicular to the flow of the cooling air already in the channels. For both of these options, the air flowing through the passages may lose axial momentum, due to the opposing flow orientations, and may also create a barrier to the momentum of the cooling air entering from the plenum.